Clock synchronization is an important aspect of communication systems. Conventional communication systems include one or more devices, such as modems, which are communicatively coupled via a network. The devices may have local clocks which may not be perfectly synchronized with one another or with the network. The variation in frequency due to lack of perfect synchronization may lead to communication errors and reduce accuracy and reliability of communication. For example, quality of communication, measured in terms of signal-to-noise ratio (SNR) may deteriorate. Existing solutions for improving synchronization in communication systems can involve synchronization signals received from external sources, such as global positioning systems (GPS). Known approaches can also involve the use of a network clock coupled to a network, such as, a fiber optic network, a cellular phone network, or a broadcast network. However, the known approaches for improving synchronization in communication systems suffer from several drawbacks, such as, high complexity in implementation, restricted availability of required resources, and often, prohibitively high costs.
A specific type of communication system known in the art is a power line communication (PLC) system. Typically, the devices in PLC systems are PLC modems. The PLC modems are communicatively coupled to a power distribution system or network. Each PLC modem has a local oscillator, which drives the local clock of the PLC modem. Variations may arise in frequencies of local oscillators in different PLC modems. For example, two local oscillators may differ in frequency to the order of +/−20 ppm. In order to provide a reliable communication, the frequencies of the receiver and the transmitter of a PLC modem need to be synchronized to one another. PLC systems possess several attractive features, such as, ease of availability and low cost. However, exposure to noise and interference from the various devices connected to the PLC system can pose severe problems to synchronization, particularly when it comes to receiver synchronization.
Accordingly, there is a need for improving synchronization in PLC systems. More specifically, there exists a need for low cost and efficient techniques for various aspects related to synchronizing devices, such as PLC modems, in PLC systems.